Bacteriology Commons^™

Aeromonas Hydrophila In Amphibians: Harmless Bystander Or Opportunistic Pathogen, Zachary P. Rivas

Honors Undergraduate Theses

For several decades amphibian populations have been declining. Historically, the bacterium A. hydrophila (Ah) was hypothesized to be the causal factor in amphibian disease and population declines. However, with the discovery of a chytrid fungus, Batrachochytrium dendrobatidis (Bd) in 1998, which was identified on the skin of amphibians during documented mortality events, Ah research became of minor interest as focus shifted to Bd. Recent studies into the immunocompromising abilities of Bd, however, have opened new questions about its relationship with Ah and their combined effects on a host.

In this study, I explore the …

Draft Genome For A Urinary Isolate Of Lactobacillus Crispatus, Travis Kyle Price, Majed Shaheen, Laurynas Kalesinskas, Kema Malki, Evann Elizabeth Hilt, Catherine Putonti, Alan J. Wolfe

Bioinformatics Faculty Publications

While Lactobacillus crispatus contributes to the stability of normal vaginal microbiota, its role in urinary health remains unclear. As part of an on-going attempt to characterize the female urinary microbiota, we report the genome sequence of an L. crispatus strain isolated from a woman displaying no lower urinary tract symptoms.

Screening For Pathogenic Escherichia Coli In The Chattahoochee River, Columbus, Georgia, Micah A. Staples

Theses and Dissertations

Escherichia coli testing is frequently used to indicate the possible presence of harmful pathogens, but E. coli itself can be pathogenic. Serotype 0157:H7, enterohemorrhagic E. coli, is likely the most medically important pathogenic strain of E. coli in the United States. In this study, we surveyed for 0157:H7 and three strains of another pathogenic subtype: enterotoxigenic E. coli. We isolated E. coli colonies from samples taken from the Chattahoochee River in Columbus, Georgia at two different locations, above and below wastewater outputs. We used PCR to test for the individual subtypes and then used a nested PCR protocol …

Determination Of Cyclic-Di-Gmp- Controlled Gene Expression In A Pharmacologically Important Bacterium, Morgan A. Stark

Undergraduate Honors Thesis Projects

The second messenger molecule cyclic dimeric GMP (c-di-GMP) regulates a myriad of processes in gram-negative bacteria. However, less is known about the roles it plays in gram-positive bacteria. Differential gene expression in three strains of the gram-positive bacterium, Streptomyces coelicolor, is being studied using RNA sequencing and Real Time PCR to gain insight into c-di-GMP signaling. The rmdA rmdB (regulator of morphology and development) double mutant was compared to the wild type strain known as MT1110. The rmdA and rmdB genes are needed for the formation of aerial mycelium, an important step in the life cycle of Streptomyces coelicolor (Hull …

Isolation And Identification Of Bacterial Endosymbionts In The Brooding Brittle Star Amphipholis Squamata, Abbey Rose Tedford

Honors Theses and Capstones

Symbiotic associations with subcuticular bacteria (SCB) have been identified and studied in numerous echinoderms, including the SCB of the brooding brittle star, Amphipholis squamata. These SCB, however, have not been studied using current next generation sequencing technologies. Previous studies on the SCB of A. squamata placed these bacteria in the genus Vibrio (γ-Proteobacteria), but subsequent studies suggested that the SCB are primarily composed of α-Proteobacteria. The present study examines the taxonomic composition of SCB associated with A. squamata from the Northwest Atlantic. DNA was extracted using a CTAB protocol and 16S rRNA sequences were amplified …

Molecular And Biochemical Signaling Underlying Arabidopsis-Bacterial/Virus/Fungal Interactions, Mohamed H. El-Shetehy

Theses and Dissertations--Plant Pathology

Systemic acquired resistance (SAR) is a form of inducible defense response triggered upon localized infection that confers broad-spectrum disease resistance against secondary infections. Several factors are known to regulate SAR and these include phenolic phytohormone salicylic acid (SA), phosphorylated sugar glycerol-3-phosphate (G3P), and dicarboxylic acid azelaic acid (AzA). This study evaluated a role for free radicals nitric oxide (NO) and reactive oxygen species (ROS) in SAR. Normal accumulation of both NO and ROS was required for normal SAR and mutations preventing NO/ROS accumulation and/or biosynthesis compromised SAR. A role for NO and ROS was further established using pharmacological approaches. Notably, …

Antibiotic Efficacy And Interaction In Escherichia Coli During Varying Nutrient Conditions, Kristina K. Millar

Scripps Senior Theses

Due to the recent rise in antibiotic resistant pathogens, and the difficulties surrounding the quest for new antibiotics, many researchers have started revisiting antibiotic interactions in hopes of finding new treatment options. The primary outcome of this project was to examine the efficacy of concomitant antibiotic use under varying nutrient conditions, to identify variations in antibiotic interactions. Antibiotic interactions were studied, utilizing E. coli as a model bacterial system, grown in four different media types. E. coli cultures were treated with streptomycin, tobramycin, erythromycin, and amikacin individually and in a pairwise fashion at varying doses. We found that at least …

Inhibition Of Bacterial Growth And Prevention Of Bacterial Adhesion With Localized Nitric Oxide Delivery, Julia Osborne

Dissertations, Master's Theses and Master's Reports

Bacterial infections continue to be a problem at the site of an indwelling medical device, and over the years, various bacterial strains have become more resistant to current antibiotic treatments. Bacterial infection at an indwelling medical device can be dangerous and affect the performance of the medical device which can ultimately lead to the failure of the device due to bacterial resistance to treatment.

Nitric Oxide (NO) has been shown to possess antibacterial properties to prevent and inhibit bacterial growth. NO releasing coatings on indwelling medical devices could provide a reduction in bacterial infections that occur at the device site …

Frequency And Etiology Of Community-Acquired Bloodstream Infection In Hospitalized Febrile Children, Tufail Soomro, Shiyam Sunder Tikmani, Sumera Aziz Ali

Community Health Sciences

Background: Blood stream infection is a serious problem that needs immediate attention and treatment. We aim to identify the frequency of common organisms in blood culture of febrile pediatric patients so that empirical antibiotic therapy can be started timely.
Methods: This cross-sectional study was conducted in pediatric ward Civil Hospital Sukkur from 1st May 2013 to 31st October 2014. Children of both genders who are between the age of one month to 15 years admitted to the pediatric ward with a fever of > 38.0 c and with a history of fever ˃ two days and whose blood culture has been …

Toxicity Of Engineered Nanomaterials To Plant Growth Promoting Rhizobacteria, Ricky W. Lewis

Theses and Dissertations--Plant and Soil Sciences

Engineered nanomaterials (ENMs) have become ubiquitous in consumer products and industrial applications, and consequently the environment. Much of the environmentally released ENMs are expected to enter terrestrial ecosystems via land application of nano-enriched biosolids to agricultural fields. Among the organisms most likely to encounter nano-enriched biosolids are the key soil bacteria known as plant growth promoting rhizobacteria (PGPR). I reviewed what is known concerning the toxicological effects of ENMs to PGPR and observed the need for high-throughput methods to evaluate lethal and sublethal toxic responses of aerobic microbes. I addressed this issue by developing high-throughput microplate assays which allowed me …

Diversity Of Free-Living Nitrogen Fixing Bacteria In The Badlands Of South Dakota, Bibha Dahal

Electronic Theses and Dissertations

Biological Nitrogen Fixation is carried out by a highly diverse group of members of the domains Bacteria and Archaea which express a nitrogenase enzyme complex and are termed diazotrophs. The best known diazotrophs form symbiotic associations with plants, but free-living nitrogen fixing bacteria also contribute a substantial amount of nitrogen to ecosystems, including arid lands. The aim of this study was to isolate free-living diazotrophs from the soil crusts of sod tables of South Dakota Badlands. Samples were obtained from sod tables and the surrounding base (matrix) in spring and fall of 2014. A culture dependent approach was used to …

The Loss Of Methanol Utilization In Methylobacteria, Justin T. Skariah

Theses and Dissertations

Methylobacteria primary uses Cl substrates as a carbon and energy source. This experiment was performed to see if Methylobacteria would lose the ability to use Cl compound methanol after prolonged exposure to multi-carbon substrates. To determine this, the bacteria was grown on MR2A3 (multi-carbon substrates) and MOM (single-carbon substrates) for multiple generations and tested for loss of function on a series of generations. These tests include streaking plates of MOM and R2A with bacteria from MR2A3 then getting a bacterial colony count and also toothpick transfers of the colonies to verify findings. After 20 generations there were no significant decrease …

The Contribution Of Marine Aggregate-Associated Bacteria To The Accumulation Of Pathogenic Bacteria In Oysters: An Agent-Based Model, Andrew M. Kramer, J. Evan Ward, Fred C. Dobbs, Melissa L. Pierce

OES Faculty Publications

Bivalves process large volumes of water, leading to their accumulation of bacteria, including potential human pathogens (e.g., vibrios). These bacteria are captured at low efficiencies when freely suspended in the water column, but they also attach to marine aggregates, which are captured with near 100% efficiency. For this reason, and because they are often enriched with heterotrophic bacteria, marine aggregates have been hypothesized to function as important transporters of bacteria into bivalves. The relative contribution of aggregates and unattached bacteria to the accumulation of these cells, however, is unknown. We developed an agent-based model to simulate accumulation of vibrio-type bacteria …

Anaplasma Marginale Actively Modulates Vacuolar Maturation During Intracellular Infection Of Its Tick Vector, Dermacentor Andersoni, Foregivemore Magunda, Chelsea Wright Thompson, David A. Schneider, Susan M. Noh

Biological Sciences Faculty Publications

ABSTRACT Tick-borne transmission of bacterial pathogens in the order Rickettsiales is responsible for diverse infectious diseases, many of them severe, in humans and animals. Transmission dynamics differ among these pathogens and are reflected in the pathogen-vector interaction. Anaplasma marginale has been shown to establish and maintain infectivity within Dermacentor spp. for weeks to months while escaping the complex network of vacuolar peptidases that are responsible for digestion ofthe tick blood meal. How this prolonged maintenance of infectivity in a potentially hostile environment is achieved has been unknown. Using the natural vector Dermacentor andersoni, we demonstrated that A. marginale …

Design And Testing Of Novel Anthrax Vaccines Utilizing A Tobacco Mosaic Virus Expression System, Ryan C. Mccomb

KGI Theses and Dissertations

Anthrax is a potentially fatal disease caused by the bacteria Bacillus anthracis. Infection and disease occur after spores gain entry into the body, germinate into vegetative bacteria, and produce toxin. Bacillus anthracis spores have been engineered as bioweapons and have been used repeatedly in warfare and terrorism to inflict casualties in military and civilian populations. Currently, only one vaccine has been approved for prevention of anthrax in the United States. This vaccine is an undefined product that is difficult to produce, requires a long vaccination schedule, and is reactogenic. Efforts to make an improved anthrax vaccine are being pursued. …

Functional Characterization Of Aggregatibacter Actinomycetemcomitans Qsebc : A Bacterial Adrengeric Receptor And Global Regulator Of Virulence., Whitney Weigel

Electronic Theses and Dissertations

In order for a pathogen to successfully colonize the host, it must be able to acquire essential nutrients and regulate gene expression to respond to environmental fluctuations. One mechanism bacteria have evolved in order to detect these fluctuations and respond is the two component signal transduction systems (TCS). Aggregatibacter actinomycetemcomitans, a dental commensal associated with localized aggressive periodontitis, contains a TCS designated QseBC that was previously shown to regulate expression of several iron acquisition genes, biofilm formation and virulence, but the activating signal was unknown []. QseBC is a conserved TCS in the Enterobacteriaceae and Pasteurellaceae, but the activating signal …

Production And Harvest Of Microalgae In Wastewater Raceways With Resource Recycling, Alexander Colin Roberts

Master's Theses

Microalgae can be grown on municipal wastewater media to both treat the wastewater and produce feedstock for algae biofuel production. However the reliability of treatment must be demonstrated, as well as high areal algae productivity on recycled wastewater media and efficient sedimentation harvesting. This processes was studied at pilot scale in the present research.

A pilot facility was operated with nine CO₂-supplemented raceway ponds, each with a 33-m² surface area and a 0.3-m depth, continuously from March 6, 2013 through September 24, 2014. The ponds were operated as three sets of triplicates with two sets continuously fed …

Detection Methods And Intestinal Adherence Of Non-O157 Shiga Toxin-Producing Escherichia Coli, Zachary R. Stromberg

School of Veterinary and Biomedical Sciences: Dissertations, Theses, and Student Research

Shiga toxin-producing Escherichia coli (STEC) are enteric pathogens of humans. Cattle serve as a reservoir and harbor STEC in their intestines. Intimin-positive STEC are referred to as enterohemorrhagic E.coli (EHEC). Seven serogroups (O26, O45, O103, O111, O121, O145, and O157) account for the majority of illness due to STEC and are hereafter referred to as STEC/EHEC-7. To improve detection, enrichment broths were compared for supporting growth of STEC-7 and STEC O104:H4 (STEC-8). In pure culture, STEC enriched in trypticase soy broth (TSB) had significantly greater growth compared to TSB containing antimicrobials. In fecal samples, E. coli broth enrichment yielded …

Cyclic Di-Gmp-Mediated Repression Of Swarming Motility By Pseudomonas Aeruginosa Pa14 Requires The Motab Stator, S. L. Kuchma, N. J. Delalez, L. M. Filkins, E. A. Snavely, J. P. Armitage, G. A. O'Toole

Dartmouth Scholarship

The second messenger cyclic diguanylate (c-di-GMP) plays a critical role in the regulation of motility. In Pseudomonas aeruginosa PA14, c-di-GMP inversely controls biofilm formation and surface swarming motility, with high levels of this dinucleotide signal stimulating biofilm formation and repressing swarming. P. aeruginosa encodes two stator complexes, MotAB and MotCD, that participate in the function of its single polar flagellum. Here we show that the repression of swarming motility requires a functional MotAB stator complex. Mutating the motAB genes restores swarming motility to a strain with artificially elevated levels of c-di-GMP as well as stimulates swarming in the wild-type strain, …

A Tail Of Two Phages: Genomic And Functional Analysis Of Listeria Monocytogenes Phages Vb_Lmos_188 And Vb_Lmos_293 Reveal The Receptor-Binding Proteins Involved In Host Specificity, Aidan Casey, Kieran Jordan, Horst Neve, Aidan Coffey, Olivia Mcauliffe

Department of Biological Sciences Publications

The physical characteristics of bacteriophages establish them as viable candidates for downstream development of pathogen detection assays and biocontrol measures. To utilize phages for such purposes, a detailed knowledge of their host interaction mechanisms is a prerequisite. There is currently a wealth of knowledge available concerning Gram-negative phage-host interaction, but little by comparison for Gram-positive phages and Listeria phages in particular. In this research, the lytic spectrum of two recently isolated Listeria monocytogenes phages (vB_LmoS_188 and vB_LmoS_293) was determined, and the genomic basis for their observed serotype 4b/4e host-specificity was investigated using comparative genomics. The late tail genes of these …